1. Field of the Invention
The present field concerns providing lighting for signs and especially a solar-powered lighting device suited for application to a variety of signs, especially real estate signs.
2. Description of Related Art
The business of advertising depends on a number of channels of mass communication to disseminate its messages. Broadcast means such as radio or television are popular because they are instantaneous and reach a large number of people. However, the traditional means of advertisement, the printed word is far from being replaced. Various publications are filled with printed inducements, and outdoor signs which are, perhaps, one of the original means for advertising are ubiquitous.
Billboards and other permanent sign installations are effective where the advertisement to be disseminated is not necessarily linked to the location of the sign. However, many signs are uniquely linked to their geographic location. When a fast food restaurant has need for a food preparer, it is likely to mount a temporary sign "Fry Chef Wanted" on the door or some other conspicuous location associated with the facility. The public naturally associates the advertisement with the restaurant and know where the job is located. Similarly, when a piece of property is put on sale, it is usual to locate a real estate sign listing the realtor and other pertinent information somewhere on the sale property. Most people are familiar with the residential real estate sign and when looking for a home to purchase may well drive through a suitable neighborhoods looking for sign to see what properties are available.
Although weekends are prime house hunting times, many people cruise around after work looking for properties for sale. Therefore, it is often extremely advantageous to have the real estate signs prominently displayed and preferably lighted. It is rare that a home owner will run an electric power cord to a real estate, or other temporary, sign. Therefore, there is a significant need for a means to illuminate such signs without depending on the local electric utilities. Solar energy, as harnessed by photovoltaic cells, is a logical way to provide electric power without a connection to the electric utilities. Several inventors have attempted to adapt solar-powered lighting to real estate and other signs.
An early patent by Stackpole (U.S. Pat. No. 4,384,317) describes the electronic circuitry necessary for a more or less permanent solar-powered sign and solar generator. Doyle (U.S. Pat. No. 5,101,329) describes a solar-powered illumination system specifically adapted to real estate signs wherein a single unit containing solar cells, electronic circuitry and lights is removably attached to a typical real estate sign. Ruocco et al. (U.S. Pat. No. 5,467,076) add an alarm and radio transmitting device to the single unit of Doyle. While these one-piece units solve part of the problem of adding temporary lighting to existing signs, there is still considerable room for improvement.
Locating the solar cells directly on the sign as taught by Ruocco et al. and Doyle has several drawbacks. First, the relatively small surface area provided by the top of a sign cross arm rarely provides sufficient area for enough solar cells. The result is that the illumination provided is less than optimally brightness and tends to be of limited duration. While it is possible to provide a larger collector surface, such a configuration tends to be ungainly when placed directly on the sign. In addition, the exactly optimal location for a sign is rarely the optimal location for receiving solar energy. For example, the sign is placed for best street viewing even though there may be an overhanging tree or other object blocking solar access.